Approximately 25 million Americans suffer from sensorineural hearing loss, which is a condition where the cochlea is unable to convert sound into nerve impulses to the brain. A cochlear implant (CI) is an array of electrodes that is surgically inserted into the cochlea to electrically stimulate the nerves responsible for hearing. As the CI is inserted into the scala tympani, delicate intracochlear structures are often damaged, which can result in decreased implant effectiveness and loss of residual hearing, especially when the implant deviates into the adjacent scala vestibuli chamber via rupture of the basilar membrane, which occurs in approximately 33% of insertions. The goal of reducing surgical trauma is especially compelling given that electric acoustic stimulation, which is a relatively new treatment directed at individuals with a considerable amount of residual hearing in the low-frequency range, is receiving greater interest, but requires atraumatic insertions to preserve the patient's residual hearing. The goal of this project is to demonstrate that magnetic guidance of CIs will reduce trauma relative to manual insertion. Magnetic guidance will be accomplished with an inexpensive clinical system, based on proven robotic and magnetic technologies developed by the investigators. In the proposed work, the investigators will pursue three specific aims: (1) They will test the conjecture that magnetic guidance will reduce insertion forces and forces against the basilar membrane compared to manual insertions, using a CI with a magnet embedded in the distal tip. Tasks include developing cochlear phantoms for experimentation, determining optimal placement of the magnetic manipulator relative to the patient, segmenting the patient's scala tympani and registering it with respect to the magnetic manipulator and insertion device, developing magnetic-guidance algorithms for free-fitting and precurved CIs for both cochleostomy and round-window insertions, developing real-time force control to be combined with magnetic guidance for improved safety and robustness, and determining if high-frequency vibration of the CI provides addition benefits. (2) They will test te conjecture that the magnet can be safely removed after CI insertion, such that the patient would not be precluded from future MRI scans. Tasks include developing a method for magnet attachment/detachment to the CI, ensuring that the cochlea is not harmed due to heating during the detachment process, and developing a method to safely remove the magnet after detachment from the CI. (3) They will verify the methods developed in the first two aims in human cadaver temporal bones combined with micro CT scans, and in live guinea pigs combined with auditory brainstem response hearing tests and histology. This project is directly relevant to the mission of the NIDCD to create devices which substitute for lost and impaired sensory and communication function. More specifically, in the 2012-2016 NIDCD Strategic Plan, in the Priority Area of Hearing and Balance Research, Priority Area 3 includes improved interventions for hearing loss, including cochlear implants.